Mechanism for preventing induced currents in telephone-lines



(No Model.) 2 Sheets-Sheet 1.

i J. W. BRENNAN 8: N. ROUSSEAU. MECHANISM FOR PREVENTING INDUCED GUREENTS IN TELEPHONE LINES.

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(No Model.) 2 Sheets-Sheet 2.

J` W, BRENNAN 8v N. ROUSSEAU. MEGHANISM FOR PREVENTING INDUGED GURRENTS IN TELEPHONE LINES.

Patented Oct. 23, 1883.

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UNITED STATES PATENT OFFICE.

JAMES lV. BRENNAN AND N ECTER ROUSSEAU, OF CHICAGO, ILLINOIS.

MECHANISM FOR PREVENTING INDUCED CURRENTS IN TELEPHONE-LINES.

SPECIFICATION forming part of Letters Patent No. 287,092, dated October 23, 1883.

Application filed November 4, 1882. (No model.)

.To all whom it may concern.:

Be it known that we, JAMES XV. BRENNAN and NEc'rER RoUssEAU, residents of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Mechanism for Neutralizing Inductive Effects of Extraneous Currents in Telephone- Lines, and we do hereby declare the following to be a full, clear, and exact description of the said invention, suicient to enable others skilled in the art to which it appertains to make and practice the same.

Vhen operating with the usual instruments over an ordinary telephonie circuit, diiculty is oftentimes experienced at the receiver in obtaining distinct enunciation of the message. Certain confused sounds, articulate or otherwise, more or less in number and of varying loudness, are frequently reproduced with the message, and tend seriously to diminish the clearness of delivery. These sounds are tracable to the fact that the line or ground connection ofthe telephonie circuit is within the field ol' some one or more other electric circuits, which, when currents are passing, reflect upon or induce in the highly-sensitive telephonie circuit the peculiarities of impulse pertaining to said extraneous circuits, so that at the receiver these are more or less audibly reproduced, together with that which is strict] y singular to the telephonie circuit itself.

The purpose of our invention is to neutralize or to destroy the inductive effects produced by extraneous currents in the telephonie circuit, so that the message will be received with clearness and comparatively free from objectionable 'foreign sounds. This purpose we have accomplished by the mechanism hereinafter described, illustrated in the accompanying drawings, and particularly set forthin the claims.

Figure l represents aview of a pole for telephone wires, showing in vertical sections modified forms of our invention applied thereto. Fig. 2 is a view, partly in section, of the form of device shown at 3 in Fig. 1, the insulator being removed. Fig. 3 is aview, partly in section and partly in side elevation, of a modified form of mechanism. Fig. 4 is an enlarged view, partly in section, of a modified form ofthe mechanism with insulator removed.

,A represents a pole provided with the usual lic sleeve F, over which passes a tube, QQ, ofV

paper or other insulating material, and around" this'tubeis wound a coil of insulated fine wire,

H, the ends of which are connected to the divided main-line wire D. From the central core, E, extends the wire c, which connects with the wire I, passing to the ground. lVhen a current of mixed character-that is to say, one having-extraneous currents imposed upon the principal current properly pertaining to the telephonie circuit-is traversing the mainline wire D from either direction, said current will be momentarily retarded as it passes from the line-wire D to the insulated coils of line wire II, by reason of the increased resistance which these coils of much lesser diameter than the main wire D oiier to its passage. The relation of the wire coils II to the core E is such that when this retardation or resistance to the main current occurs there is induced in said core E an opposite electric impulse, which constantly drains away to ground through the wires c and I. It is plain that this induced current will reflect the peculiarities of the primary from which it is derived, which in this instance being of a composite or mixed nature makes the induced current of like* character. Both the telephonie and the extraneous induced currents unite in the production of the induced electric impulse developed in core E, and each suffers diminution because of the constant discharge of the induced current to the ground. Experience has demonstrated, however, that they suil'er diminution very unequally, lcastwise, that the extraneous induction effects developed in the telephonie current being the weaker are gradually eliminated as a succession of resistance-coils are presented in the main-line cir- Cuit, while the primary telephonie current ICO in any given line.

In the form of device shown attached to the pole at 2 the insulator C is held upon the wooden pin C, which enters the pole. This pin C is bored out, and withinlit is placed the metallic core E, around which, in this inst ance, is directly fitted the paper tube G, having the coil H,- of fine insulated wire, wrapped thereon. The ends h of the coil pass through holes in the pin C and connect with the divided main wire D, and from the metal core E extends the wire e to the ground-wire I. It will be noticed that in this form we have dispensed with the metallic sleeve F, which, although in practice is found advantageous, is not regarded as absolutely essential.

In the form of device illustrated at 3 in Fig. 1, and in Fig. 2, a wooden pin, C', supports the insulator C and contains the metal core E, the metal sleeve F, the insulating paper tube G, and fine-wire coil H. The ends of the fine wire extend in this case over the top of or through the wooden pin, and are connected to flat metal strips 7b2 on the outside of the same, which are joined to the short insulated wire h, leading to the main line D. To the top of the central core, E, isv attached a broad metal strip, E', which extends'down the sides of the wooden pin, between but wholly separate from strips h2, and through said core E connects with the wire c and ground-wire I. In the normal condition of the line the circuit will be from main wire D through insulated wire 71.', strip h2, fine-wire coil H, to companion strip h2, insulated wire h', 'and thence to main wire D 5 but should the linebecome surch arged,

as in case of electric storms, endangering the safety of coil H and its connections, the near proximity of the fiat strips E to they strips h2 will afford ready means for the excessive or abnormal current to leap or bridge the space between the two sets of strips, passing thus from strips E to core E, connecting-wire e, wire I, and thence to ground.

In order to prevent induction-currents in .telephone-lines, it has been heretofore proposed to place beneath the main-line wire a dead-wire,7 the ends of which were grounded.

In the modified form of our invention shown in Figs. 34 and 4 it is proposed to use a deadwire, X, stretched from the cross-arms B of two adjoining poles. The insulator C is supported upon the bored-out wooden pin C', which contains the metal core F', the metal sleeve F in contact therewith, the paper tube nects with the dead-wire X at one the telephonie circuit.

G, and the coil H, of fine insulated wire, heretofore described. In this form, however, the core E is made of copper,and to the top of the core is connected a strip, El, also of copper, which extends down the side of pin C and conpole. The sleeveF is of zinc, and to it is attached the zinc strip F', which extends down the side of pin C and connects with the wire I, leading to the ground. At the adjoining pole the zinc strip F v is connected to the dead-wire, and the copper strip E'l is attached to the ground-wire I. By thus constructing the cores E, sleeves F, and strips E2 F of zinc and copper and connecting them up, as described, a slight voltaic current is established, which passes'through the supple-A mental Wire and assists in neutralizing the inductive effects of the extraneous currents upon In this modified construction it is to be understood that the main telephonie circuit yet continues in vmanner heretofore detailedthat is to say, the current passes either from main wire D, as shown at 1 2,Fig. 1, through connecting-wire h, coil H, opposite connecting-wire h, to line, or else (as in 3, Fig. 1, and Figs. 2, 3, and 4) from main wire D through insulated wire h', strip h3, fine-wire coil H, to companion strip h2, insulated wire h', and thence again to line. In this latter instance (3, Fig. 1, and Figs. 2 and 4) it will be understood that the strips act in conjunction with strips E2 F and their ground-connections to relieve the line from excessive currents' which would tend to destroy the fine-wire coils H, as already detailedvmore particularly in describing 3, Figs. 1 and 2. The induced currents developed in core E by the primary current in coil H will pass (3, Fig. 1, and Fig. 2) by wire e, which is joined to core E, as at IOO 2, Fig. 1, 4to wire I, thence to ground, or else,

Figs. 3, 4, will pass from core E by strip F] and wire I to ground, or by metal sleeve F,

strip F', and wire I to ground.

Vhile we have set out in the foregoing dej scription what we regard to be the best embodiments of our invention, it is obvious that modifications of the same may be made without departing from the spirit thereof. Thus,

for example, good results may be obtained by simply making a coil of the main wire at suit- .able intervals along the line and passing an insulated core having ground-connections through such coil, although we have foundv in vpractice that the fine-wire coil is more advantageous. In fact,`a great variety of ways will i readily suggest themselves to the person skilled in the art by which the main line can be exposed at intervals tothe inductive action of a conducting-body held in close proximity there- ;to, yet insulated therefrom and having shortcircuit ground-connections, which, broadly stated, is the underlying principle embodied in the several forms of our invention.

Having thus described the invention, what we claim as new, and desire to secure byv Letters Patent, is

' 1. In a telephonie circuit, the combination,

with the main-line Wire, of a conducting-body arranged at suitable intervals in close proximity thereto, but insulated therefrom and having` a ground-connection, substantially as described.

2. In a telephonie circuit, the combination, with the main-line Wire, of a Wire coil, and a core for said coil, insulated therefrom and having` a ground-Wire connection, substantially as described.

3. In a telephonie circuit, the combination, with the divided main wire, of anne-Wire coil connecting,` the parts of said main Wire, and a core for said coil, insulated therefrom and having a ground-wire connection, substantially as described.

4. In a telephonie circuit, the combination, with the main Wire, of a Wire coil, a metallic sleeve insulated from said coil, and a core for and a sleeve of copper, a dead-Wire connected at one end to a sleeve and at the other end to a core, and a ground-wire connection for one sleeve and one core, substantiall5T as described.

JAMES IV. BRENNAN. NEGTER ROUSSEAU.

XVitn esses:

GEORGE l?. FISHER, Jr., FRANK S. BLANCHARD. 

